WO2016015590A1

WO2016015590A1 - Controller and control method for alternating current contactor

Info

Publication number: WO2016015590A1
Application number: PCT/CN2015/084895
Authority: WO
Inventors: 余飞; 顾长恂; 葛顺锋; 张地; 冯宇刚; 史亚闻; 曾萍
Original assignee: 上海电科电器科技有限公司; 浙江正泰电器股份有限公司
Priority date: 2014-07-30
Filing date: 2015-07-23
Publication date: 2016-02-04
Also published as: US10256063B2; ES2781192T3; CN105321770A; US20170213677A1; CA2956170A1; CA2956170C; EP3176803A4; EP3176803B1; EP3176803A1; CN105321770B

Abstract

A controller for an alternating current contactor. The controller comprises: a filtering and rectification circuit (101, 102), which filters and rectifies external alternating current; an electromagnet component (103), which is driven by the output of the filtering and rectification circuit and performs an attraction, holding or releasing action; a power transistor circuit (104), which is connected to the electromagnet component; and a microcontroller (112), which controls on or off of the power transistor circuit to control the electromagnet component to perform the attraction, holding or releasing action. The controller further comprises: a voltage control loop, which provides a voltage feedback signal to the microcontroller so that the microcontroller generates a control signal according to the voltage feedback signal, wherein the control signal is a PWM control signal having different duty cycles during the attraction and holding of the electromagnet component so that the current does not exceed a predetermined current threshold during the attraction and holding of the electromagnet component; and a current control loop, which provides a current feedback signal to the microcontroller so that the microcontroller turns off the power transistor circuit upon detecting an overcurrent exceeding the current threshold.

Description

AC contactor controller and control method

Technical field

This invention relates to the field of low voltage electrical appliances and, more particularly, to control techniques for AC contactors.

Background technique

The electronic control technology of the AC contactor is mostly based on the control circuit built by the single-chip or discrete components. The PWM control method drives the electromagnet of the AC contactor to reliably attract, hold or release. The overall technical parameters need to comply with GB14048.4. The requirements specified in the standard and achieve energy saving purposes.

The Chinese patent application entitled "Energy Saver for AC Contactor" discloses an energy saver for an AC contactor, including a peripheral circuit connected to the AC contactor, and the application number is CN201210196762.4, the publication number is CN102709118A. A signal processor connected to the peripheral circuit; the signal processor includes a comparison circuit, a zero-crossing detection circuit, a pulse width modulation circuit, a selection circuit, a low voltage detection circuit, and a signal synthesis circuit. The energy saver disclosed in CN102709118A can only adjust the PWM pulse width of the small current in the electromagnet holding phase under different control voltages, and in the pick-up phase, the PWM pulse width is not adjustable, only through a number of fixed power frequency pulses. The driving electromagnet pull-in action can not control the amplitude and dynamic characteristics of the pull-in current, which has a great influence on the pick-up characteristics of the contactor, and is particularly unsuitable for frequent operation, which affects the life of the contactor and is not conducive to energy saving; The PWM frequency of the small current in the hold phase is fixed to the power frequency signal. Although the holding current of the 20ms time level is relatively constant current, the dynamic range of the small current within 20ms is large, and the operating frequency band belongs to the human ear. In the range, the noise of the contactor can not be further reduced, and the life of the contactor is also affected. Moreover, it cannot realize the automatic adjustment of the wide range of the control voltage, so it cannot be applied to the occasion where the control voltage fluctuates greatly, and at the same time, to meet different control For voltage usage requirements, different energy savers and coils need to be configured with matching parameters, and the product model and phase are added. Increased storage management costs and stocking costs.

The application number is CN201210530495.X, the publication number is CN103021735A, and the Chinese patent application entitled "AC contactor intelligent control module with high-speed pulse width modulation function" discloses an AC contactor intelligent control module with high-speed pulse width modulation function. The utility model comprises an AC/DC power supply, wherein the AC/DC power supply is sequentially supplied with a rectifying and filtering circuit and a power electronic switch for supplying an AC contactor coil; and further comprising a voltage sampling circuit, a single chip control system, a dual DA conversion circuit, and a sawtooth wave generation. Circuit, square wave clock signal, high speed pulse width modulator, bootstrap circuit, compensation circuit, switching point detection circuit, Hall current sensor, freewheeling circuit, low voltage holding circuit and constant voltage/constant current automatic switching circuit. CN103021735A discloses two completely different control strategies for the electromagnet suction and hold phase. The suction phase passes the current feedback loop, adopts the PWM control mode, detects the coil current through the Hall current sensor, and the single chip microcomputer controls the adjustment coil through the current feedback signal. Excitation current; after the end of the suction process, it switches to the low voltage holding circuit through a trigger switching point detecting circuit, and directly supplies DC power to the electromagnet coil in the holding phase to drive the electromagnet to work. In this way, in order to achieve the normal operation of the contactor and achieve the energy-saving purpose of large current absorption and small current maintenance, the entire control module not only adopts the suction and holding two sets of control loops, but also adds the Hall current sensor circuit and the trigger switching point detection circuit. Such considerable hardware circuit and software overhead not only increase the cost but also occupy more space, which is particularly disadvantageous for the application of the contactor with smaller current specifications, and the use is limited. For the high current specification contactor, the coil is kept. The required energy is large, and the above-mentioned low-voltage holding circuit provides sufficient energy to keep the contactor in a holding state, and requires a sufficient capacity to output a certain power, further increasing the cost.

In addition, in the above prior art solution, a freewheeling circuit is disposed in the electromagnet coil circuit. On the contactor of the large current specification, the coil current is large in the coil, and the presence of the freewheeling circuit causes the coil current of the contactor during the release process. The change is too slow, making the release process longer and seriously affecting the release performance of the contactor.

Summary of the invention

The invention aims to propose a controller and a control method for an AC contactor.

According to an embodiment of the invention, a controller for an AC contactor is provided, comprising:

a filter rectifier circuit connected to an external alternating current to filter and rectify the external alternating current;

The electromagnet assembly is driven by the output of the filter rectifier circuit to perform an action of sucking, holding or releasing;

a power tube circuit connected to the electromagnet assembly;

a microcontroller, connected to the power tube circuit, the microcontroller outputs a control signal to the power tube circuit, and the power tube circuit is turned on or off according to the control signal to control the action of the electromagnet assembly to perform the pull-in, hold or release;

The controller also includes:

a voltage control loop, the voltage control loop provides a voltage feedback signal to the microcontroller, and the microcontroller generates the control signal according to the voltage feedback signal and outputs the control signal to the power tube circuit, wherein the electromagnet assembly is engaged and held The control signals are PWM control signals having different duty ratios, and the PWM control signals having different duty ratios cause the current to not exceed a predetermined current threshold during the electromagnet assembly during pick-and-hold;

The current control loop, the current control loop provides a current feedback signal to the microcontroller, and the microcontroller turns off the power transistor circuit when the current control loop detects an overcurrent that exceeds the current threshold.

In one embodiment, the controller further includes a switching circuit that adjusts the current threshold according to different phases:

During the pick-up phase of the electromagnet assembly, the switching circuit sets a first current threshold;

During the holding phase of the electromagnet assembly, the switching circuit sets a second current threshold;

The first current threshold is greater than the second current threshold.

In one embodiment, the controller further includes a PLC control module. When the PLC module is enabled, the PLC control signal is output to the microcontroller, and the microcontroller controls the power tube circuit according to the PLC control signal to control the electromagnet assembly to perform the pull-in. , hold or release action.

In one embodiment, the electromagnet assembly includes an electromagnet coil, a freewheeling circuit, and a demagnetization circuit;

The freewheeling circuit is connected to the electromagnet coil, and the freewheeling circuit operates to maintain the current in the electromagnet coil during the pickup phase and the holding phase of the electromagnet coil;

The demagnetization circuit is connected to the electromagnet coil, and during the release phase of the electromagnet coil, the demagnetization circuit breaker The demagnetization circuit utilizes the characteristic that the current across the coil of the electromagnet cannot be abruptly changed, and raises the voltage across the coil of the electromagnet so that the energy of the coil of the electromagnet is quickly dissipated.

In one embodiment, the controller of the AC contactor comprises:

a filtering module, the external alternating current is connected to the input end of the filtering module;

a rectifier module, wherein an input end of the rectifier module is connected to an output end of the filter module;

An electromagnet coil, a freewheeling circuit, a demagnetization circuit, a first end of the electromagnet coil is connected to an output end of the rectifier module, and a second end of the electromagnet coil is connected to an input end of the freewheeling circuit and the demagnetization circuit, and a freewheeling circuit And an output end of the demagnetization circuit is connected to the first end of the electromagnet coil;

a power MOS transistor and a MOS transistor driving device, the source of the power MOS transistor is connected to the second end of the electromagnet coil, and the output end of the MOS transistor driving device is connected to the gate of the power MOS transistor;

Switching circuit, the input end of the switching circuit is connected to the drain of the power MOS tube, and the output end of the switching circuit is connected to the rectifier module;

a voltage detecting device, wherein an input end of the voltage detecting device is connected to an output end of the rectifier module, and an output end of the voltage detecting device outputs a voltage feedback signal;

a current detecting device, the input end of the current detecting device is connected to the drain of the power MOS tube, and the output end of the current detecting device outputs a current feedback signal;

PLC control module, the input end of the PLC control module receives the logic control signal, and the output end of the PLC control module outputs the PLC control signal;

a microcontroller that receives a voltage feedback signal from a voltage detecting device, a current feedback signal from the current detecting device, and a PLC control signal from a PLC control module, the microcontroller to the demagnetizing circuit, the MOS tube driving circuit, and the switching circuit Output control signal;

The power module, the input end of the power module is connected to the output end of the rectifier module, and the power module provides DC power for the demagnetization circuit, the MOS tube driving device, the current detecting device, the voltage detecting device, the microcontroller, and the PLC control module.

In one embodiment, the input of the filter module has two input terminals through which external alternating current is input to the filter module.

In one embodiment, the power module outputs a DC power source having a different voltage, wherein

The power supply module provides a DC power supply for the demagnetization circuit of 15V;

The DC power supply provided by the power module for the MOS tube driving device is 12V;

The power supply module provides 5V for the current detection device, voltage detection device, microcontroller and PLC control module.

In one embodiment, the PLC control module includes an AND gate, one input of the AND gate is an enable terminal, and the other input terminal of the AND gate is a control terminal, and the control terminal receives an external control signal through the isolation circuit;

When the enable terminal is enabled, the control signal received by the control terminal is input to the AND gate through the isolation circuit. The signal of the enable terminal and the signal of the control terminal are output by the AND gate after the AND gate operation, and the output of the AND gate is used as The output of the PLC control module outputs a PLC control signal.

In one embodiment, the first input pin of the microcontroller is coupled to the output of the voltage sensing device, the first input pin receives a voltage feedback signal; and the second input pin of the microcontroller is coupled to the output of the current sensing device The second input pin receives the current feedback signal; the third input pin of the microcontroller is connected to the output end of the PLC control module, and the third input pin receives the PLC control signal; the first output pin of the microcontroller is connected Going to the control end of the demagnetization circuit, the first output pin outputs a demagnetization control signal; the second output pin of the microcontroller is connected to the control end of the MOS tube driving device, and the second output pin outputs the MOS tube driving signal; The third output pin of the controller is connected to the control end of the switching circuit, and the third output pin outputs a switching control signal.

According to an embodiment of the invention, a method for controlling an AC contactor is provided, including

Filtering and rectifying the external alternating current, and driving the rectified output to drive the electromagnet assembly;

Controlling the turning on or off of the power tube circuit by the microcontroller, and causing the electromagnet assembly to perform the action of sucking, holding or releasing through the turning on or off of the power tube circuit;

Sampling the voltage feedback signal, the microcontroller generates a control signal according to the voltage feedback signal to control the power tube circuit, so that the electromagnet assembly performs the action of sucking, holding or releasing, wherein during the process of attracting and holding the electromagnet assembly, The control signals are PWM control signals having different duty cycles, the PWM control signals having different duty cycles such that the current does not exceed a predetermined current threshold during the pick-up and hold of the electromagnet assembly;

Sampling the current feedback signal, when the current control loop detects an overcurrent current exceeding a current threshold, the microcontroller turns off the power tube circuit, and the switching current circuit adjusts the current threshold according to different stages: in the suction phase of the electromagnet assembly, The switching circuit sets a first current threshold, in a holding phase of the electromagnet assembly, the switching circuit sets a second current threshold, and the first current threshold is greater than the second current threshold;

A PLC module is enabled, and the PLC module outputs a PLC control signal to the microcontroller when enabled, and the microcontroller directly controls the power tube circuit according to the PLC control signal to cause the electromagnet assembly to perform the action of sucking, holding or releasing.

The controller and control method of the AC contactor of the invention adopts adaptive voltage and current double loop control, and provides a switchable PLC control mode, so that the contactor can reliably attract and maintain in the suction phase in a wide voltage range. The stage operates at a substantially constant current and is quickly disconnected during the release phase. It has the characteristics of small size, low cost, simple switching and low power consumption. The controller and control method can be applied to contactors of all current levels.

DRAWINGS

The above and other features, aspects, and advantages of the present invention will become more apparent from the description of the appended claims appended claims

1 discloses a circuit schematic of a controller of an AC contactor in accordance with an embodiment of the present invention.

2 is a block diagram showing a PLC control module in a controller of an AC contactor in accordance with an embodiment of the present invention.

3 discloses a circuit diagram of a switching circuit in a controller of an AC contactor in accordance with an embodiment of the present invention.

4 is a circuit diagram of a demagnetization circuit in a controller of an AC contactor in accordance with an embodiment of the present invention.

FIG. 5 discloses logic of a control method of an AC contactor according to an embodiment of the present invention. Figure.

detailed description

The invention provides a controller for an AC contactor, comprising a filter rectifier circuit, an electromagnet assembly, a power tube circuit and a microcontroller. The filter rectifier circuit is connected to external AC power to filter and rectify the external AC power. The electromagnet assembly is driven by the output of the filter rectifier circuit to perform a pull-in, hold or release action. The power tube circuit is connected to the electromagnet assembly. The microcontroller is connected to the power tube circuit, and the microcontroller outputs a control signal to the power tube circuit, and the power tube circuit is turned on or off according to the control signal to control the action of the electromagnet assembly to perform the pull-in, hold or release.

The control mode of the controller is as follows: a voltage feedback signal is obtained through a voltage control loop, and a current feedback signal is obtained through a current control loop. The voltage control loop provides a voltage feedback signal to the microcontroller, and the microcontroller generates a control signal according to the voltage feedback signal and outputs the control signal to the power tube circuit, wherein the control signal is during the pick-up and hold of the electromagnet assembly PWM control signals having different duty cycles are output to the power tube circuit such that the current does not exceed a predetermined current threshold during pick-up and hold of the electromagnet assembly. The current control loop provides a current feedback signal to the microcontroller, and the microcontroller turns off the power transistor circuit when the current control loop detects an overcurrent that exceeds the current threshold.

A PLC control module is also provided, and the PLC control module is connected to the microcontroller. When the PLC module is enabled, the PLC control signal is output to the microcontroller, and the microcontroller controls the power tube circuit according to the PLC control signal to control the electromagnet assembly to perform suction. The action of closing, holding or releasing. The PLC module provides an extended control method for controlling the pull-in, hold or release of the electromagnet directly through the microcontroller using weak current signals. As an extension of the control mode of the PLC module, it is a supplement to the external power control mode (strong power control).

In order to adapt to different peak currents of the electromagnet assembly during the pick-up phase and the holding phase, a switching circuit is also provided, and the switching circuit adjusts the current threshold according to different phases: in the pickup phase of the electromagnet assembly, the switching circuit sets the first current threshold. The switching circuit sets a second current threshold during the holding phase of the electromagnet assembly. The first current threshold is greater than the second current threshold.

In order to achieve a reliable suction in the suction phase, a steady current in the holding phase and a rapid release in the release phase. The controller of the present invention includes an electromagnet coil, a freewheeling circuit, and a demagnetization circuit in the electromagnet assembly. The freewheeling circuit is connected to the electromagnet coil, and during the pull-in phase and the holding phase of the electromagnet coil, the freewheeling circuit operates to maintain the current in the electromagnet coil. The demagnetization circuit is connected to the electromagnet coil. During the release phase of the electromagnet coil, the demagnetization circuit works. The demagnetization circuit utilizes the characteristic that the current at both ends of the electromagnet coil cannot be abruptly, and raises the voltage across the coil of the electromagnet so that the electromagnet coil The energy is quickly dissipated.

Referring to Figures 1-4, a circuit schematic of a controller of an AC contactor in accordance with an embodiment of the present invention, and a circuit diagram of some of the components and circuits therein are disclosed.

Referring to Figure 1, Figure 1 discloses a circuit schematic of a controller of an AC contactor in accordance with an embodiment of the present invention. In Figure 1, the thicker lines represent the power loop (higher power loop) and the thinner lines represent the control loop (weak circuit). The controller includes:

The filtering module 101 has an external alternating current connected to the input end of the filtering module 101. In the embodiment shown in FIG. 1, the input of the filter module 101 has two input terminals A1, A2 through which external alternating current is input to the filter module 101.

The rectifier module 102 has an input end connected to the output of the filter module 101. The filtering module 101 and the rectifying module 102 filter and rectify the external alternating current to generate a pulsed direct current, and the rectifying module 102 outputs the pulsed direct current to the electromagnet coil 103, the power module 108 and the voltage detecting device 111. The rectifier module 102 is also coupled to the switching circuit 105 for receiving feedback signals from the switching circuit 105.

The electromagnet coil 103, the freewheeling circuit 106, and the demagnetization circuit 107 together constitute an electromagnet assembly of the controller. The first end M1 of the electromagnet coil is connected to the output end of the rectifying module 102, and the second end M2 of the electromagnet coil is connected to the input terminals of the freewheeling circuit 106 and the demagnetizing circuit 107, the freewheeling circuit 106 and the demagnetizing circuit 107 The output is connected to the first end M1 of the electromagnet coil. The freewheeling circuit 106 and the demagnetizing circuit 107 are substantially parallel, and the freewheeling circuit 106 and the demagnetizing current 107 alternately operate at different stages, as will be described in more detail below.

Power MOS transistor 104 and MOS transistor driver 109, source of power MOS transistor 104 S is connected to the second terminal M2 of the electromagnet coil 103, and the output of the MOS transistor driving device 109 is connected to the gate G of the power MOS transistor 104. The drain D of the power MOS transistor 104 is connected to the switching circuit 105, and the control terminal of the MOS transistor driving device 109 is controlled by the microcontroller 112, and the microcontroller 112 controls the turning-on or turn-off of the power MOS transistor 104 through the MOS transistor driving circuit 109. .

The switching circuit 105 has an input terminal connected to the drain D of the power MOS transistor 104, an output terminal of the switching circuit 105 connected to the rectifier module 102, and a control terminal of the switching circuit 105 controlled by the microcontroller 112.

The voltage detecting means 111, the input end of the voltage detecting means 111 is connected to the output end of the rectifying module 102, and the output end of the voltage detecting means 111 outputs a voltage feedback signal to the microcontroller 112.

The current detecting device 110 has an input terminal connected to the drain D of the power MOS transistor 104, and an output terminal of the current detecting device 110 outputs a current feedback signal to the microcontroller 112.

The PLC control module 113, the input end of the PLC control module 113 receives the logic control signal, and the output terminal PLCON of the PLC control module 113 outputs the PLC control signal. As an extended control mode, the PLC control module 113 can directly control the microcontroller 112 through the PLC control signal. Referring to FIG. 2, FIG. 2 discloses a block diagram of a PLC control module in a controller of an AC contactor in accordance with an embodiment of the present invention. The PLC control module 113 includes an AND gate. One input of the AND gate is the enable terminal PLCEN, and the other input of the AND gate is the control terminal PLCD. The control terminal PLCD receives an external control signal through the isolation circuit. In one embodiment, the enable terminal PLCEN can be connected to a unit of the DIP switch, and the input of the enable signal is implemented by the unit's DIP switch. The isolation circuit can be implemented by an optocoupler isolation circuit. When PLCEN is enabled, the control signal of the PLCD of the control terminal can be input to the AND gate through the optocoupler isolation circuit. The signal input by the enable terminal PLCEN and the signal input by the control terminal PLCD are processed in the AND gate to generate a PLC control signal, and outputted to the microcontroller 112 by the output terminal PLCON.

The microcontroller 112 receives the voltage feedback signal from the voltage detecting device 111, the current feedback signal from the current detecting device 110, and the PLC control signal from the PLC control module 113, and the microcontroller 112 goes to the demagnetizing circuit 107, MOS tube drive circuit 109 And the switching circuit 105 outputs a control signal. In the embodiment shown in FIG. 1, the first input pin PI1 of the microcontroller 112 is coupled to the output of the voltage detecting device 111, and the first input pin PI1 receives the voltage feedback signal. The second input pin PI2 of the microcontroller 112 is coupled to the output of the current sensing device 110, and the second input pin PI2 receives the current feedback signal. The third input pin PI3 of the microcontroller 112 is connected to the output terminal PLCON of the PLC control module 113, and the third input pin PI3 receives the PLC control signal. The first output pin PO1 of the microcontroller 112 is connected to the control terminal of the demagnetization circuit 107, and the first output pin PO1 outputs a demagnetization control signal. The second output pin PO2 of the microcontroller 112 is connected to the control terminal of the MOS transistor driving device 109, and the second output pin PO2 outputs a MOS transistor driving signal. The third output pin PO3 of the microcontroller 112 is connected to the control terminal of the switching circuit 105, and the third output pin PO3 outputs a switching control signal.

The power module 108, the input end of the power module 108 is connected to the output end of the rectifier module 102, and the power module 108 is a demagnetization circuit 107, a MOS tube driving device 109, a current detecting device 110, a voltage detecting device 111, a microcontroller 112, and a PLC. The control module 113 provides a DC power source. In the embodiment shown in FIG. 1, the power module 108 outputs DC power supplies having different voltages, wherein the DC power supply provided by the power module 108 to the demagnetization circuit 107 is 15V. The DC power supply provided by the power module 108 to the MOS tube driving device 109 is 12V. The DC power supply provided by the power module 108 for the current detecting device 110, the voltage detecting device 111, the microcontroller 112, and the PLC control module 113 is 5V.

The frequency of the AC control voltage input by the external AC power source is 50 Hz, and is rectified by the rectifier module 102 to become 100 Hz. The voltage detecting circuit 111 processes the rectified voltage signal to obtain a voltage feedback signal, and the voltage feedback signal is sent to the microcontroller 112. The voltage sampling port is the first input pin PI1. The microcontroller 112 sets the sampling period to 10 ms, and obtains the effective value of the control voltage by performing a true RMS operation on the sampling point, and uses this as a basis for controlling the operation of the electromagnet assembly. The working voltage of the contactor is 110-230V. According to the provisions of GB14048.4-2010, the contactor must be reliably sucked under the control power supply voltage of 85%~110%, and released and completely disconnected at 20%~75%. From this, it is determined that the pull-in voltage is 90 to 255 V, the holding voltage is 80 to 255 V, and the release voltage is 80 V. The release voltage and the minimum value of the pull-in voltage have a hysteresis voltage of 10V. The setting of the threshold voltage ensures reliable attraction and release of the electromagnet and prevents the chattering from being caused by the chattering. The microcontroller 112 outputs a control signal to the power tube circuit according to the voltage range of the feedback voltage, and controls the electromagnet to perform a corresponding action through the power tube circuit. If the feedback voltage is the pull-in voltage, the control electromagnet performs the pull-in action, and if the feedback voltage is the hold voltage, the control electromagnet performs the hold action, and if the feedback voltage is the release voltage, the control electromagnet performs the release action.

As described above, the contactor has a pull-in voltage of 90 to 255 V and a holding voltage of 80 to 255 V, both of which are in a range. In the pull-in and hold phases, the feedback voltage may be different. In order to ensure reliable contact and retention of the contactor under different control voltages, PWM technology is applied to reliably control the solenoid coil. The microcontroller 112 controls the current in the pull-in and hold phases by outputting PWM waveforms having different duty cycles to the MOS transistor driving device and the power MOS transistor. The pull-in, hold PWM duty cycle at different control voltages is stored in the FLASH or EEPROM of the microcontroller 112, and the associated PWM duty cycle is read from the FLASH or EEPROM when the microcontroller 112 is powered up. After sampling the control voltage of 2 cycles (20 ms), the microcontroller 112 issues a set PWM waveform according to the control voltage (the control voltage is a voltage feedback signal output by the voltage detecting device 111) for the pull-in phase control. At this stage, the control voltage is continuously detected by the voltage feedback means 111 to modify the PWM duty cycle in real time. After several cycles (generally greater than 60ms, depending on the characteristics of the contactor, the precondition is to ensure that the contactor can be reliably attracted), the pull-in action should be completed, at which point the microcontroller 112 then The acquired control voltage adjusts the PWM duty cycle to the hold interval and continuously adjusts. This control method in which the duty ratio of the duty cycle with the control voltage (voltage feedback signal) is adjusted in real time during the pull-in and hold phases is advantageous to achieve the best suction-force cooperation and reduce the core bounce, which is beneficial to realize dynamic control and prolong contactor life. . When the control voltage (ie, the voltage feedback signal) is in the normal pull-in and hold interval, ie, 80 to 255V, the microcontroller 112 continues to control based on the control voltage and outputs a PWM having a corresponding duty cycle. If the feedback voltage is lower than 80V, the contactor performs a release action. If the feedback voltage is higher than the upper limit of the pull-in voltage, such as 255V, then the fault may cause the voltage to be too high, and the circuit needs to be turned off in time to protect. Device.

During the use of the contactor, there is often a phenomenon in which the overheating causes the coil insulation damage to cause a short circuit. In the absence of protection, an overcurrent caused by a short circuit can cause damage to the coil and control circuitry. In addition, installing a faulty voltage level coil can also cause overcurrent. In this regard, the controller of the present invention provides a current detecting device 110 that collects a current feedback signal and provides it to the microcontroller 112. The microcontroller 112 compares the current feedback signal collected by the current detecting device 110 with a current threshold. When the current feedback signal is greater than the threshold, it indicates that an overcurrent occurs, and at this time, the microcontroller 112 stops the output of the PWM signal to turn off the power transistor circuit.

Since the electromagnet assembly differs in the operating state of the suction phase and the holding phase, the amount of current allowed in the suction phase and the holding phase is different, the suction phase allows for a larger current, and the retention phase allows a smaller current. Therefore, the microcontroller 112 should set different current thresholds for control corresponding to different phases.

Switching circuit 105 is used to achieve adjustment of the current threshold at different stages. 3 discloses a circuit diagram of a switching circuit in a controller of an AC contactor in accordance with an embodiment of the present invention. As shown in FIG. 3, the switching circuit 105 includes resistors R4, R5, R6, R7, R8, R9, and R10, a capacitor C1, and a MOS transistor Q2. The resistors R4, R5 and R6 are connected in parallel, and the R7 is connected in series with the MOS transistor Q2 and then connected in parallel with the resistors R4, R5 and R6. Resistors R9 and R10 serve as auxiliary resistors for the control terminal, and resistor R9 is the control terminal START of switching circuit 105, which is coupled to microcontroller 112. Resistor R8 and capacitor C1 act as auxiliary resistors and capacitors for the input and output. The Icoil terminal shown in FIG. 3 is the output terminal of the switching circuit 105. The In terminal shown in FIG. 3 is an input terminal of the switching circuit 105 and is connected to the drain D of the power MOS transistor 104. When the contactor is in the pickup phase, the microcontroller 112 outputs a control signal to the control terminal START, and the pull-in phase control signal is at a high level. During the conduction of the power MOS transistor 104, the MOS transistor Q2 is turned on, and the resistors R4 and R5 are turned on. R6 and R7 form a parallel relationship. The voltage signal on the resistor network is output from Icoil to the microcontroller 112 as a feedback signal. The microcontroller 112 sets a corresponding larger current threshold according to the feedback signal. After the end of the pull-in phase, the signal output from the microcontroller 112 to START is low, the MOS transistor Q2 is turned off, and the voltage signal on the resistor R7 is output from the Icoil to the microcontroller 112 as feedback. Based on the feedback signal, the microcontroller 112 sets a corresponding smaller current threshold for the hold phase. Since the voltage signal on the resistor network and the voltage signal on R7 are different, the microcontroller 112 can achieve the goal of segmentation control according to the difference of the signal.

In order to achieve a quick release of the electromagnet assembly, the controller of the present invention also includes a demagnetization circuit 107 in the electromagnet assembly. 4 is a circuit diagram of a demagnetization circuit in a controller of an AC contactor in accordance with an embodiment of the present invention. As shown in FIG. 4, the demagnetization circuit 107 is connected to both ends of the electromagnet coil 103. In Fig. 4, the electromagnet coil 103 is represented by L1, and both ends of L1 are the M1 end and the M2 end, respectively. The demagnetization circuit 107 includes voltage regulators VR1, VR2, and VR3, a diode D1, a MOS transistor Q1, resistors R1, R2, and R3, and capacitors C2 and C3. The +D15V terminal is the power input and is connected to the power module. The DeMagnet terminal is a control terminal and is connected to the microcontroller 112. When the contactor is in the pull-in or hold phase, the signal output from the microcontroller 112 to the DeMagnet terminal is at a high level. During the turn-on of the power MOS transistor 104, the MOS transistor Q1 is not turned on, and the holding current flows in the L1; During the turn-off of the transistor 104, the MOS transistor Q1 is turned on, and L1 flows through the MOS transistor Q1 and the diode D1 through the freewheeling current; when the contactor is in the release phase, the signal output from the microcontroller 112 to the DeMagnet terminal is low, the MOS transistor Q1 is turned off, at this time, the power MOS transistor 104 is also in the off state, and L1 quickly releases energy through the voltage regulator tubes VR2 and VR3 to achieve the purpose of rapid release of the electromagnet.

The invention also discloses a control method of an AC contactor, comprising:

Sampling the voltage feedback signal, the microcontroller generates a control signal according to the voltage feedback signal to control the power tube circuit, so that the electromagnet assembly performs the action of sucking, holding or releasing, wherein during the process of picking and holding the electromagnet assembly, the control The signals are PWM control signals having different duty ratios, and the PWM control signals having different duty ratios are output to the power tube circuit such that the current does not exceed a predetermined current threshold during the pick-up and hold of the electromagnet assembly;

Sampling the current feedback signal when the current control loop detects an overcurrent that exceeds the current threshold The microcontroller turns off the power tube circuit, and the switching current circuit adjusts the current threshold according to different stages: in the pickup phase of the electromagnet assembly, the switching circuit sets a first current threshold, in the holding phase of the electromagnet assembly, The switching circuit sets a second current threshold, and the first current threshold is greater than the second current threshold;

FIG. 5 discloses a logic diagram of a method of controlling an AC contactor in accordance with an embodiment of the present invention. As shown in FIG. 5, the control method of the AC contactor of the present invention includes the following process:

The system initializes and performs an initialization task.

Check if the interrupt flag bit is present and enter the control process when the interrupt flag bit appears.

Measure the control voltage.

Check if the PLC control signal PLCON exists. If PLCON=1, it means that the PLC control signal does not exist. At this time, it is controlled by the control voltage. If PLCON=0, the PLC control signal is considered to exist and directly controlled by the PLC control signal.

In the case of PLCON=1, it is judged whether or not the control voltage > the pull-in voltage is established.

If the control voltage > pull-in voltage is established, it is judged whether the contactor is in the pull-in position. If the contactor is not in the pull-in position, adjust the duty cycle of the PWM in the pull-in phase, set the peak of the pull-in current, turn on the power MOS tube, perform the pull-in action, start the pull-in delay, and adjust the current after the delay arrives. The peak value is the holding current peak. If the contactor is in the pull-in position, set the hold current peak directly. After the setting of the hold current peak is completed, the duty ratio of the PWM in the hold phase is adjusted. After completing this operation, return to the step of detecting the interrupt flag and wait for the next interrupt flag to appear.

If the control voltage > the pull-in voltage is established, it is further determined whether the hold voltage < control voltage < the pull-in voltage is established.

If the holding voltage <control voltage < the pull-in voltage is established, it is judged whether or not the contactor is in the pull-in position. When the contactor is in the pull-in position, the hold current peak is set, and then the hold phase is adjusted. The duty cycle of the PWM. After completing this operation, return to the step of detecting the interrupt flag and wait for the next interrupt flag to appear. If the contactor is not in the pull-in position, complete this operation directly, return to the step of detecting the interrupt flag, and wait for the next interrupt flag to appear.

If the holding voltage <control voltage < the pull-in voltage does not hold, the control voltage is considered to be the holding voltage. At this point, it is detected whether the contactor is in the suction position. When the control voltage <hold voltage or PLCON=0, the same control logic is entered. At this time, it is judged whether the contactor is in the pull-in position. If the contactor is not in the pull-in position, the operation is directly completed and the detection interrupt flag is returned. The bit step waits for the next interrupt flag to appear. If the contactor is in the suction position, the power MOS tube is turned off, the demagnetization circuit is started to release the contactor, and the release delay is started. After the delay arrives, the operation is completed, and the process returns to the detection interrupt flag bit, waiting for the next time. The occurrence of an interrupt flag bit.

The above embodiments are provided to those skilled in the art to implement or use the present invention, and those skilled in the art can make various modifications or changes to the above embodiments without departing from the inventive concept. The scope of the invention is not limited by the embodiments described above, but should be the maximum range of the inventive features as claimed.

Claims

A controller for an AC contactor, comprising:

a filter rectifier circuit connected to an external alternating current to filter and rectify the external alternating current;

The electromagnet assembly is driven by the output of the filter rectifier circuit to perform an action of sucking, holding or releasing;

a power tube circuit connected to the electromagnet assembly;

a microcontroller, connected to the power tube circuit, the microcontroller outputs a control signal to the power tube circuit, and the power tube circuit is turned on or off according to the control signal to control the action of the electromagnet assembly to perform the pull-in, hold or release;

The controller is further characterized by:

a voltage control loop, the voltage control loop provides a voltage feedback signal to the microcontroller, and the microcontroller generates the control signal according to the voltage feedback signal and outputs the control signal to the power tube circuit, wherein the electromagnet assembly is sucked and held In the process, the control signals are PWM control signals having different duty ratios, and the PWM control signals having different duty ratios cause the current to not exceed a predetermined current threshold during the electromagnet assembly during pick-and-hold;

The current control loop, the current control loop provides a current feedback signal to the microcontroller, and the microcontroller turns off the power transistor circuit when the current control loop detects an overcurrent that exceeds the current threshold.
A controller for an AC contactor according to claim 1, further comprising a switching circuit that adjusts said current threshold according to different phases:

The switching circuit sets a first current threshold during a pickup phase of the electromagnet assembly;

The switching circuit sets a second current threshold during a holding phase of the electromagnet assembly;

The first current threshold is greater than the second current threshold.
The controller of the AC contactor according to claim 1, further comprising a PLC control module, wherein the PLC module outputs a PLC control signal to the microcontroller when enabled, and the micro control The controller controls the power tube circuit according to the PLC control signal to control the action of the electromagnet assembly to perform the pull-in, hold or release.
A controller for an AC contactor according to claim 1, wherein said electromagnet assembly comprises an electromagnet coil, a freewheeling circuit and a demagnetization circuit;

The freewheeling circuit is connected to the electromagnet coil, and the freewheeling circuit operates to maintain the current in the electromagnet coil during the suction phase and the holding phase of the electromagnet coil;

The demagnetization circuit is connected to the electromagnet coil. During the release phase of the electromagnet coil, the demagnetization circuit works. The demagnetization circuit uses the characteristic that the current at both ends of the electromagnet coil cannot be abruptly, and raises the voltage across the coil of the electromagnet. The energy of the electromagnet coil is quickly dissipated.
The controller of the AC contactor according to any one of claims 1 to 4, comprising:

a filtering module (101), the external alternating current is connected to the input end of the filtering module (101);

a rectifier module (102), an input end of the rectifier module (102) is connected to an output end of the filter module (101);

An electromagnet coil (103), a freewheeling circuit (106), a demagnetization circuit (107), a first end (M1) of the electromagnet coil is connected to an output end of the rectifier module (102), and a second end of the electromagnet coil ( M2) is connected to the input terminals of the freewheeling circuit (106) and the demagnetization circuit (107), the output ends of the freewheeling circuit (106) and the demagnetization circuit (107) are connected to the first end (M1) of the electromagnet coil;

The power MOS transistor (104) and the MOS transistor driving device (109), the source (S) of the power MOS transistor (104) is connected to the second end (M2) of the electromagnet coil (103), and the MOS transistor driving device (109) The output is connected to the gate (G) of the power MOS transistor (104);

a switching circuit (105), the input end of the switching circuit (105) is connected to the drain (D) of the power MOS transistor (104), and the output of the switching circuit (105) is connected to the rectifier module (102);

a voltage detecting device (111), an input end of the voltage detecting device (111) is connected to an output end of the rectifying module (102), and an output end of the voltage detecting device (111) outputs a voltage feedback signal;

a current detecting device (110), an input end of the current detecting device (110) is connected to a drain (D) of the power MOS transistor (104), and an output end of the current detecting device (110) outputs a current feedback signal;

The PLC control module (113), the input end of the PLC control module (113) receives the logic control signal, and the output end (PLCON) of the PLC control module (113) outputs the PLC control signal;

a microcontroller (112) that receives a voltage feedback signal from the voltage detecting device (111), a current feedback signal from the current detecting device (110), and a PLC control signal from the PLC control module (113), The microcontroller (112) outputs a control signal to the demagnetization circuit (107), the MOS transistor drive circuit (109), and the switching circuit (105);

The power module (108), the input end of the power module (108) is connected to the output end of the rectifier module (102), and the power module (108) is a demagnetization circuit (107), a MOS tube driving device (109), and a current detecting device ( 110) The voltage detecting device (111), the microcontroller (112), and the PLC control module (113) provide DC power.
The controller of the AC contactor according to claim 5, characterized in that the input end of the filter module (101) has two input terminals (A1, A2) through which external alternating current is passed (A1) A2) Input to the filtering module (101).
The controller of the AC contactor according to claim 5, wherein the power module (108) outputs a DC power source having a different voltage, wherein

The power supply module (108) provides a DC power supply for the demagnetization circuit (107) of 15V;

The power supply module (108) provides a DC power supply for the MOS tube driving device (109) of 12V;

The power module (108) provides a DC power supply of 5V for the current detecting device (110), the voltage detecting device (111), the microcontroller (112), and the PLC control module (113).
A controller for an AC contactor according to claim 5, wherein said PLC control module (113) includes an AND gate, and an input of said AND gate is an enable terminal (PLCEN). The other input end of the AND gate is a control terminal (PLCD), and the control terminal (PLCD) receives an external control signal through the isolation circuit;

When the enable terminal (PLCEN) is enabled, the control signal received by the control terminal (PLCD) is input to the AND gate through the isolation circuit. The signal of the enable terminal (PLCEN) and the signal of the control terminal (PLCD) pass the AND gate operation. The output of the AND gate is output, and the output of the AND gate is used as the output of the PLC control module (PLCON) to output the PLC control signal.
A controller for an AC contactor according to claim 5, wherein

A first input pin (PI1) of the microcontroller (112) is coupled to an output of the voltage detecting device (111), and the first input pin (PI1) receives a voltage feedback signal;

A second input pin (PI2) of the microcontroller (112) is coupled to an output of the current sensing device (110), and a second input pin (PI2) receives a current feedback signal;

The third input pin (PI3) of the microcontroller (112) is connected to the output end (PLCON) of the PLC control module (113), and the third input pin (PI3) receives the PLC control signal;

The first output pin (PO1) of the microcontroller (112) is connected to the control end of the demagnetization circuit (107), and the first output pin (PO1) outputs a demagnetization control signal;

The second output pin (PO2) of the microcontroller (112) is connected to the control end of the MOS tube driving device (109), and the second output pin (PO2) outputs the MOS tube driving signal;

The third output pin (PO3) of the microcontroller (112) is connected to the control terminal of the switching circuit (105), and the third output pin (PO3) outputs a switching control signal.
A method for controlling an AC contactor, comprising:

Filtering and rectifying the external alternating current, and driving the rectified output to drive the electromagnet assembly;

Controlling the turning on or off of the power tube circuit by the microcontroller, and causing the electromagnet assembly to perform the action of sucking, holding or releasing through the turning on or off of the power tube circuit;

Sampling the voltage feedback signal, the microcontroller generates a control signal according to the voltage feedback signal to control the power tube circuit, so that the electromagnet assembly performs the action of sucking, holding or releasing, wherein the electromagnetic During the pick-up and hold of the iron assembly, the control signals are PWM control signals having different duty cycles, and the PWM control signals having different duty cycles cause current during the pick-up and hold of the electromagnet assembly Not exceeding the predetermined current threshold; sampling the current feedback signal, when the current control loop detects an overcurrent exceeding the current threshold, the microcontroller turns off the power tube circuit, and a switching circuit adjusts the current threshold according to different stages: in the electromagnetic a switching phase of the iron assembly, the switching circuit is configured to set a first current threshold, and in the holding phase of the electromagnet assembly, the switching circuit sets a second current threshold, and the first current threshold is greater than the second current threshold;

A PLC module is enabled, and the PLC module outputs a PLC control signal to the microcontroller when enabled, and the microcontroller directly controls the power tube circuit according to the PLC control signal to cause the electromagnet assembly to perform the action of sucking, holding or releasing.